Cocking trigger mechanisms which are specifically designed for automatic pistols are known from the Daewoo DP 51 C automatic pistol. In contrast to an ordinary pistol in which the hammer element and the drive part together form a single component, namely, the hammer, the Daewoo DP 51 C pistol has no permanent fixed connection between its drive part and its hammer element. The hammer element is easily braked by friction, but is otherwise mounted to pivot freely in the pistol stock. The hammer element, which is designed as a cocking lever and provided with a thumb rest for manual cocking, is forced forward by the drive part when the weapon is fired.
This known pistol can be used like any double-action pistol. Specifically, when the drive part is uncocked and the hammer element is situated in its rest position (i.e., when the pistol is in its fully uncocked position), the hammer element and drive part can be moved backward together by applying a relatively large force to the trigger. When the trigger is pulled rearwardly a sufficient distance, the hammer element and the drive part retract (i.e., move forward) such that the hammer element strikes the firing pin and a shot is fired. When the hammer element and the uncocked drive part are moved to the rear by means of the handle of the hammer element or by the breech of the loaded pistol, the hammer element remains in its rear position and the drive part remains in its cocked position as a single cock until the trigger is released. Compared to the fully uncocked position discussed above, a relatively low amount of force is required to pull the trigger when the weapon is in this fully cocked position.
When the weapon is in its fully cocked position, it is possible to push the hammer element forward into its rest position while the drive part remains in its cocked position without firing a shot. This position of the trigger mechanism can be referred to as the "increased readiness position". Since the hammer element is situated in its rest position when the weapon is in its increased readiness position, the hammer element does not protrude from the weapon. As a result, the pistol can be kept in a pocket or shoulder holster without fear that the hammer element will accidentally catch on an external element (for example, on the cover of the pocket or on the material of a jacket) when the pistol is pulled. When the weapon is in the increased readiness position, a relatively low force is required to fire the pistol. Specifically, when the weapon is in the increased readiness position, the force to cock the striker spring does not need to be applied via the trigger to fire the pistol. Instead, only the frictional resistance of the hammer element, which is pivoted rearward by itself since the drive part is already secured in its cocked position, must be overcome to reach the pressure point.
Whereas, in the fully cocked position (wherein the hammer element is positioned close to its rear position) a limited force exerted on the trigger is sufficient to fire the shot, in the "increased readiness position" the frictional force of the hammer element (i.e., the force required to draw the hammer element rearward from its at rest position) must be overcome to fire the pistol. As a result, the danger of unintentional firing a shot when the pistol is in its increased readiness position is reduced as compared to the fully cocked position.
However, the reduced danger associated with the increased readiness position of the Daewoo DP 51 C pistol can be somewhat illusory. For example, it is easily possible for the hammer element to approach its rear end position if the handle of the hammer element catches on clothing, on a branch, or on some other obstruction, so that, while the shooter is relying on the "increased readiness position", the fully cocked position is actually present. The danger of unintentionally firing a shot, which is supposed to be reduced in the increased readiness position, is then quite real. Moreover, the frictional force required to move the hammer element from its rest position to its rear position is highly subject to the condition of the weapon. Wear, oil with high lubricating effect, and/or rust film can drastically alter this frictional force under some circumstances. Dust, fine sand, frost which thickens the weapon lubricant, etc. can also have such an effect. Finally, operation of the Daewoo DP 51 C is complicated because of the three possible states of the trigger mechanism. This is disadvantageous because the simplest possible operation is desired in a military weapon. Simple design of the cocking trigger mechanism is, however, advantageous.
To achieve a comparable "increased readiness position" it is proposed in EP Patents 0,077,790 and 0,154,356 that the striker spring should only be partially cocked during loading of an automatic pistol, as is also the case in the Austrian calvary pistol Roth-Steyr model 1907. As a result, the shooter is required to fully cock the striker spring during each shot via the trigger. However, it is additionally proposed in the aforementioned patents that a tension spring counteract the striker spring so that the force required for final cocking of the striker spring is partially applied by the tension spring. With a fully cocked striker spring, the tension spring is disconnected and the firing pin can retract.
These pistols are disadvantageous because their complicated decoupling mechanisms are prone to soiling and corrosion. In addition, these known pistols have the shortcoming that they are continuously cocked, even if only partly. In an unfavorable case only a weak impact on the firing pin can be sufficient to fire a cartridge, should the other safety precautions fail. Another shortcoming of these pistols is the fact that breech movement is always required to cock the firing pin into the partially cocked position. For example, if striking of the firing pin is impeded by water that has penetrated the weapon or too much oil in the weapon (in wet pistols or pistols that are too heavily oiled), then failure of a nondefective cartridge can occur. If the shooter has only one free hand, (for example, because he is bracing himself with the other hand), then he cannot reload the pistol, so that it fails. In contrast, if a cocking trigger mechanism were present, he could simply retract it again, which in the described case would fire the cartridge with high probability and would return the pistol to full readiness.
On the other hand, pistols of the foregoing type are advantageous in that their trigger resistance can be adjusted by adjusting the tension spring, and in that the same type of operation is always present during shooting (i.e., they are relatively simple to operate).